This invention relates to a method of printing.
In pixel based printing systems such as dot matrix ribbon printing, or thermal transfer printing which utilises a carrier or carrier which carries print medium such as ink, (known in thermal printing, as ribbon or foil), one major expense for a user is the cost of the ribbon or foil.
According to the invention we provide a method of printing utilising a printing apparatus having a print head with an array of printing elements each of which is individually selectable in a plurality of pixel row positions along an adjacent substrate to transfer a pixel of print medium from a carrier onto the adjacent substrate, the array extending laterally with respect to a direction of relative movement between the carrier and substrate, and the print head, characterised in that the method includes the steps of
(a) carrying out a first printing operation by means of causing relative movement between the substrate and carrier, and the print head, such that the print head moves relative to a first area of the carrier from a start position to an end position whilst printing elements from a first set of adjacent printing elements of the laterally extending array are selected to transfer a first set of pixels of print medium from the area of the carrier onto the substrate to produce an image having height less than one half of the width of the carrier;
(b) causing relative movement between the print head and the carrier to reposition the print head at the start position of the carrier;
(c) causing relative movement between the carrier and the substrate to present fresh substrate adjacent to the area of the carrier, and
(d) carrying out a second printing operation by means of causing relative movement between the fresh substrate and carrier, and the print head, such that the print head moves again relative to the area of the carrier from the start position to the end position whilst printing elements from a second set of adjacent printing elements laterally disposed with respect to the first set of adjacent printing elements are selected to transfer a second set of pixels of print medium from the area of the carrier onto the fresh substrate, to produce a second image having a height less than one half of the width of the carrier.
The invention offers a way for a user to save the cost of thermal printing ribbon or foil, or other carrier and print medium where the image to be printed is substantially narrower than i.e. at least half of the width of the carrier.
By xe2x80x9cfresh substratexe2x80x9d we mean an entirely fresh substrate, such as a different label, or a further part of the same substrate, onto which pixels of print medium have not previously been transferred from the carrier.
By means of the invention, two separate substrates or separate areas of substrate can be printed for example, with the same information, but the printing apparatus only consumes one area of ribbon or foil.
Particularly where the image is very narrow compared to the width of the carrier, the method may be repeated several times for the same area of carrier, with each relative movement between substrate and carrier, and the print head, utilising a different set of printing elements to transfer different pixels of print medium onto substrate.
After each printing operation the printing head may be moved e.g. laterally, away from the carrier and substrate, and held a short distance away from the carrier whilst the carrier and/or substrate are moved in preparation for the next printing operation, and then moved e.g. laterally, back towards the carrier and substrate.
In one embodiment, the relative movement between the substrate and carrier, and the print head, is produced by movement of the print head whilst the substrate and carrier are held generally stationary relative to a base.
In another embodiment, the relative movement between the substrate and carrier, and the print head, is produced by movement of the substrate and carrier whilst the print head is held generally stationary relative to a base.
The invention is particularly but not exclusively applicable to thermal transfer printing, where the print medium comprises ink carried on a carrier comprising a continuous backing carrier, and the printing elements are energised to produce heat to transfer pixels of ink from the carrier onto a substrate.
In such an application, there are typically at least six, commonly eight or twelve or more printing elements per millimetre of printing head, arranged in a single line array. The printing elements may, however, be arranged in a multiple line, or other non-single line array.
However the invention may be applied to any other dot based printing system such as a dot matrix printer which utilises a woven ribbon as a carrier for ink and where printing elements are arranged in an array.
According to a second aspect of the invention we provide a printing apparatus adapted for performing the method of the first aspect of the invention.